1. Field of the Invention
The present invention relates to a camera having a liquid crystal display.
2. Description of the Related Art
In a known digital still camera, in general, a liquid crystal display (LCD) is provided to confirm an object image taken by the camera or during photographing of an object. The LCD has an advantage that more than one person can view the object or the photographed object image at one time, but has the disadvantage of the object image not being able to be viewed clearly in bright surroundings, since the quantity of light of the back light is limited. There is also the disadvantage of an increased power consumption of the camera. Moreover, in a known digital camera in which an optical finder is provided in addition to the LCD to locate an optical image of a photographing lens system to be viewed, however, if an optical finder is provided, the overall manufacturing cost is increased.
It is an object of the present invention to provide a camera having a liquid crystal display in which two modes, i.e., a mode in which the LCD is directly viewed and a mode in which the LCD is viewed through an eyepiece lens system can be selected without providing an optical finder through which an optical image formed by a photographing lens system is viewed.
To achieve the object mentioned above, a camera is provided, including a liquid crystal display in which an image formed by a photographing lens system of the camera is indicated; an ocular viewing optical system which includes a half-mirror surface and an eyepiece lens system, the half-mirror surface reflecting the image of the liquid crystal display toward the eyepiece lens system, so that the reflected image can be viewed through the eyepiece lens system; and a direct viewing optical system for viewing the image of the liquid crystal display through the half-mirror surface.
If the direct viewing optical system and the ocular viewing optical system are provided in a finder unit which is detachably attached to the camera, it is possible to provide two view systems without increasing the size of the camera.
Preferably, the direct viewing optical system includes a first prism which is provided with a first surface parallel with the liquid crystal display, a second surface opposed to the first surface at an angle inclined with respect to the first surface, a third surface intersecting the first and second surfaces, and a fourth surface opposed to the third surface; and a second prism which is provided with a first surface parallel with the second surface of the first prism, and a second surface parallel with the first surface of the first prism. The second surface of the first prism and the first surface of the second prism opposed thereto are provided with a common half-mirror surface.
Preferably, the angles of the surfaces of the first prism are set so that light emitted from the liquid crystal display and incident upon the first surface of the first prism is reflected by the second surface thereof, defined by the half-mirror surface, toward the first surface, is internally reflected by the first surface toward the third surface, is reflected by the third surface toward the fourth surface, and is transmitted through and emitted from the fourth surface.
In an embodiment, a third prism is provided which makes the light emitted from the fourth surface of the first prism incident upon the eyepiece lens system.
If an opening and closing device is provided for opening and closing a direct view window of the direct viewing optical system, no harmful light entering the ocular optical system through the direct optical view system.
If a detection device is provided for detecting the operation of the direct view window opening and closing device; and a control device responsive to the detection device for controlling the illuminance of back light of the liquid crystal display, not only can the liquid crystal display be more clearly viewed but also the electric power consumption can be reduced.
If a detection device for detecting the operation of the opening and closing device for the direct view window and a control device responsive to the detection device for controlling the illuminance of back lighting of the liquid crystal display are provided.
The present disclosure relates to subject matter contained in Japanese Patent Application No.2000-72793 (filed on Mar. 15, 2000) which is expressly incorporated herein by reference in its entirety.